Want a super-visual science fair project that feels like magic but is actually real science? This color mixing experiment is perfect for Kindergarten-2nd grade: simple supplies, quick setup, and results kids can clearly see, record, and explain.
Big idea: When you mix two primary colors (red, yellow, blue), you can make new colors called secondary colors (orange, green, purple).
- Time: 20-45 minutes
- Difficulty: Easy
- Mess level: Low (but use paper towels!)
Science Fair Question
What new colors do you make when you mix two primary colors?
Optional “Level Up” question: How does changing the number of drops change the shade (light or dark) of the new color?
Hypothesis (Kid-Friendly)
I think when I mix red and yellow I will make orange, when I mix yellow and blue I will make green, and when I mix blue and red I will make purple.
Variables (Make It a Fair Test)
- Independent variable (what you change): Which two colors you mix (red + yellow, yellow + blue, blue + red)
- Dependent variable (what you observe): The new color you get
- Controls (keep the same): Same amount of water in each cup, same number of drops (at first), same cup size, same lighting
Materials
- 6 clear cups (or small clear jars)
- Water
- Food coloring: red, yellow, blue
- 3 droppers or spoons (or use one dropper and rinse between colors)
- Paper towels (for spills)
- Labels or masking tape + marker
- White paper (to hold behind cups so colors show up)
Step-by-Step Procedure
Tip: Put white paper behind your cups so the colors are easy to see.
- Label three cups: Red, Yellow, Blue.
- Fill each of those cups with the same amount of water (about halfway).
- Add 5 drops of the matching food coloring to each cup (5 drops red in “Red,” etc.). Stir gently.
- Label three more cups: Red + Yellow, Yellow + Blue, Blue + Red.
- Pour the same amount of Red water into the Red + Yellow cup, then pour the same amount of Yellow water into it. Stir.
- Repeat for Yellow + Blue and Blue + Red.
- Hold each cup in front of white paper. Observe the new colors and record what you see in the data table.
Data Table (Copy This)
| Mix | Red | Yellow | Blue | What color did you get? |
|---|---|---|---|---|
| Red + Yellow | X | X | ____________ | |
| Yellow + Blue | X | X | ____________ | |
| Blue + Red | X | X | ____________ |
Expected Results
- Red + Yellow → Orange
- Yellow + Blue → Green
- Blue + Red → Purple
Bonus observation: If you add more drops of one color than the other, the new color changes shade (for example, more red than yellow makes a more reddish orange).
Scientific Explanation (Simple + True)
Food coloring acts like a dye. Dyes and paints use subtractive color mixing. That means the colored dye absorbs (subtracts) some light and reflects the rest into our eyes.
When you mix two dyes, each dye absorbs some of the light. The leftover light that still reflects is what you see as the new color. That’s why red and yellow look orange together, yellow and blue look green, and blue and red look purple.
Kids Version (What to Say on the Day of the Fair)
“My question was: What new colors do you make when you mix two primary colors? I kept it fair by using the same amount of water and the same number of drops each time. I tested three mixes. I learned that mixing primary colors makes secondary colors: orange, green, and purple.”
Level Up (Optional for 1st-2nd Grade)
Turn this into a bigger experiment by testing different ratios (different numbers of drops) and comparing shades.
| Mix | Drops (Color A) | Drops (Color B) | Result color | Shade (lighter/darker?) |
|---|---|---|---|---|
| Red + Yellow | 5 red | 5 yellow | ________ | ________ |
| Red + Yellow | 8 red | 2 yellow | ________ | ________ |
| Red + Yellow | 2 red | 8 yellow | ________ | ________ |
New question: Does using more of one color change the shade of the mixed color?
Parent/Coach Tips (Make It Easy + Board-Ready)
- Use a muffin tin or egg carton as a “cup holder” to prevent spills.
- Take 3-5 photos during the experiment for the display board (setup, mixing, final colors).
- If droppers are hard, use measuring spoons (like 1 teaspoon of each colored water) to keep amounts equal.
- Write results in thick marker so judges can see from a distance.
Safety Notes
- Food coloring can stain skin and clothes-use an old shirt or apron.
- Do not drink the colored water.
- Wipe spills right away to avoid stains on tables.
Display Board Layout (Simple and Strong)
- Title: “Mixing Primary Colors”
- Question: What new colors do you make when you mix two primary colors?
- Hypothesis: (One sentence)
- Materials: Short list
- Steps: 4-6 bullets
- Results: Data table + photos
- Conclusion: What you learned
Conclusion Starter (Fill in the Blank)
“I learned that when you mix ____________ and ____________, you get ____________. My hypothesis was (right / not right) because ____________.”
Judge Questions to Practice
- What did you change in your test?
- What stayed the same to make it a fair test?
- Which mix surprised you most?
- If you did it again, what would you test next?